Yes you are correct about the PCV. It divides rear pedal pressure between front and rear calipers with a bias toward the fronts.
The secondary master cylinder provides pressure to the rear caliper when the front brake lever is applied. It is the mechanism that Honda uses to link the front brake to the rear brake. There is no shared hydraulic circuit to do this but rather a mechanical one. The left brake caliper is mounted on a bracket that pivots on a lug on the lower left fork slider. THe SMC is on the top of the left front caliper bracket and is aligned fore and aft with a short clevis and pushrod that fixes to a second lug near the top of the fork slider. When the front brake lever is applied the LF caliper pivots forward a few millimeters and since the pushrod is fixed in length it applies pressure into the secondary master cylinder. Pressure is sent to the rear caliper when the front wheel is turning and the front brake is applied. The front wheel has to be turning.
If you don't mind lying on the floor next to your motorcycle you can test the SMC action. Lay down with your head toward the front in such a way you can push the rear wheel with your right foot, causing it to turn. While pushing the rear wheel, reach up and push the left front caliper forward. It won't move much, a few mm, but in doing so the center pistons in the rear caliper will press against the rear disk and stop the wheel from turning (applying brake).